Automotive fuel systems generally incorporate a fuel filter connected to the end to the fuel pickup line within the fuel tank. When a fuel pump is placed within the tank, then the filter is connected to the intake end of the pump. In any event, the filter may be capable of separating water as well as particulate matter from fuel as shown in U.S. Pat. No. 2,788,125. Many current tanks are of a shallow, flat configuration which makes desirable the withdrawal of the fuel from a point quite close to the bottom in order to make use of substantially all the fuel tank capacity. Since these shallower tanks of larger horizontal area have a greater capacity per inch of fuel depth, it becomes important that it be possible to remove the last inch or so of fuel from the bottom of the tank and this has made mecessary positioning the filter against, or at least in close proximity to the bottom wall of the tank. Filters designed to be disposed adjacent or against the bottom wall of the automotive fuel tank are shown representatively by U.S. Pat. No. 2,788,125; 2,826,372 and 3,900,397. With the advent of intank fuel pumps, it is possible to create a good suction at the filter, and this, combined with the necessity of disposing the filter against the bottom of the tank, has made it necessary to insure that fuel flow through the filter walls is not blocked either by the filter collapsing or by the filter wall being sucked against the tank wall thereby shutting off fuel flow.
U.S. Pat. Nos. 1,999,628 and 3,826,372 show spacer means within fuel filters for holding the walls apart. In addition, there is a filter commercially available having a plastic foam insert that is intended to hold the filter walls in distended position. This foam spacer is liable to have pieces break off which can enter the fuel system causing serious difficulties and the spacer means shown in the aforementioned patents substantially raise the cost of the filter.
It is therefore desirable that a filter be provided which can be economically manufactured without expensive modifications in existing manufacturing processes, and which filter will have its walls held apart despite the creation of a strong fuel suction within the filter, and wherein means are provided for holding the filter spaced slightly from the fuel tank bottom or other wall so that essentially all of the fuel in the tank may be drawn into the filter without the filter wall being sucked against the bottom wall of the tank blocking fuel flow.